Dual-Mode Wheat Germ Agglutinin Labeling - A Versatile Cell Segmentation Strategy for High-Resolution LA-ICP-TOFMS Bioimaging

Single-cell analysis by laser ablation inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-TOFMS) enables high-resolution mapping of elemental distributions and cellular phenotypes. Segmentation of individual cells necessitates labeling of both nuclei and membranes, the latter often requiring extensive tissue-specific optimization. In this study, we present a broadly applicable segmentation protocol based on wheat germ agglutinin (WGA), a lectin that binds to N-acetylglucosamine and sialic acid residues ubiquitously expressed on the cell membrane. By combining fluorescently labeled WGA with a metal-tagged anti-WGA antibody, we introduce a dual-labeling strategy compatible with both fluorescence microscopy and LA-ICP-TOFMS, enabling cross-validation of membrane labeling and enhancing segmentation accuracy. With recent advancements in laser ablation technology, such as higher repetition rates and submicrometer spot sizes, high-resolution imaging across large sample areas has become increasingly feasible. The robust, high-contrast membrane labeling achieved with our method facilitates precise cell segmentation at these resolutions and enhances the quality of the downstream single-cell data analysis. Beyond that, our approach reduces staining costs, streamlines workflows, and provides a scalable alternative to existing membrane-labeling strategies.